1. Field
Embodiments relate to a resist underlayer composition and a method of manufacturing a semiconductor integrated circuit device using the same.
2. Description of the Related Art
Lithography processes may minimize reflection between a resist layer and a substrate in order to increase resolution. For this reason, an anti-reflective coating (ARC) may be used between the resist layer and the substrate to improve the resolution. However, since the anti-reflective coating material may have a similar basic composition as a resist material, the anti-reflective coating material may exhibit a poor etch selectivity with respect to the resist layer with an image imprinted therein. Therefore, an additional lithography process in a subsequent etching process may be performed. Also, resist materials may not have sufficient resistance to the subsequent etching process. When a resist layer is thin, when a substrate to be etched is thick, when an etch depth is deep, or when a particular etchant is required for a particular substrate, a resist underlayer may be used.
The resist underlayer may include, e.g., two layers having an excellent etch selectivity. Referring to FIG. 1, a first resist underlayer 3, which may be formed of an organic material, may be formed on a substrate 1. The substrate 1 may be formed of a silicon oxide layer. A second resist underlayer 5 may be formed on the first resist underlayer 3. Finally, a resist layer 7 may be formed on the second resist underlayer 5. Since the second resist underlayer 5 may have a higher etch selectivity with respect to the resist layer 7 than the substrate 1, a pattern may be easily transferred even when a thin resist layer 7 is used. The first resist underlayer 3 may be etched and the pattern may be transferred by using the second resist underlayer 5 having a pattern thereon as a mask. Then, the pattern may be transferred to the substrate 1 using the first resist underlayer 3 as a mask. To sum up, a substrate may be etched to a desired depth by using a thinner resist layer 7. The second resist underlayer may be a layer formed under the resist layer and may function as an anti-reflective coating material. The second resist underlayer may have an optical characteristic in that it may absorb light emitted from an exposer and may not reflect the light. Particularly, as semiconductor devices are miniaturized to have a linewidth of only tens of nanometers, semiconductor fabrication processes may require a delicate control of the optical characteristics.